The first new map added after Valorant launched was Icebox.
Icebox was introduced in October 2020, several months after Valorant’s June 2, 2020 release. It became the game’s fifth standard map and expanded the map design with a distinctly Arctic setting. Its snowy industrial environment includes two sites, vertical routes, zip lines, ropes, and large open areas that reward careful control of sightlines.
Icebox was also notable because it introduced more verticality and unusual movement options than the original launch maps. A and B sites have different layouts and tactical demands, while elevated platforms and ropes can create unexpected angles. The map has received multiple layout changes over time as Riot adjusted problem areas and competitive balance.
Pearl, Fracture, and Breeze were added later. Pearl arrived in 2022, Fracture in 2021, and Breeze was introduced in 2021, so none predates Icebox. The question refers to the first post-launch map, not the first map ever created for Valorant.